Safety device for hoist platforms



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l R. F. WARRY SAFETY DEVICE FOR HOIST PLATFORMS Filed July 16, M349jatented july l0,

SAFETY DEVICE FOR HOIST PLATFORMS Reginald Frank Warry, Twickenham,England,

assigner to R. F. Warry Limited, London, England, a British companyApplication July 16, 1949, Serial No. 105,118 In Great Britain January24, 1948 6 Claims. l

This invention relates to safety devices for use Awith hoist platforms,lift cages and the like.

Various forms of safety devices have been proposed heretofore for usewith platforms or cages of hoists, lifts and the like for the purpose ofautomatically arresting the descent of the platform or vcage in theevent of a cable by which it is suspended and drawn along a hoist frameor guideways of a shaft breaking or coming adrift so that it loses itsload-carrying tension. Such safety devices sometimes take the form ofsplit cones accommodated in tapered sleeves, the cable being threadedthrough the split cone so that consequent upon fracture of the cable thecone produces a `wedging action on the cable. Also, cam actuated deviceshave been proposed hereto- 'fore adapted consequent upon the freeing ofthe tension of the cable from spring means associated with the platformor cage to seize or bite against the hoist frame or guideways in thelift shaft. These and other known previously proposed safety devices aregenerally of a somewhat complicated or expensive nature and frequentlyfail by reason of their becoming worn away and/or slipping relatively tothe frame or guide.

The object of the present invention is to provide a highly positive,simple and very strong safety device suitable for use with hoists orlift cages in which the platform or cage travels along a vertical ornearly vertical frame. For example the present invention is particularlyuseful in connection with the form of hoist described in my applicationNo. 18,270 of 1946 in which the platform of a transportable hoistcarries rollers by which it is guided along the appropriate anglebarmembers of a girder type of hoist frame.

The present invention is broadly characterised in that the cable bywhich the hoist platform or lift cage, hereinafter referred to as theplatform, is drawn upwards along guideways is operatively connected tothe platform via an abutment member which, by the tension of the saidcable is held against a locking member formed with abutments adapted,when the cable breaks or comes adrift, to bite against adjacent verticalguideways but normally held clear of said guideways, said locking memberbeing held by the tension of the cable in the normal or inoperativeposition by engaging a stop on the platform, spring means yieldinglyopposing the tension of the cable being provided across the lockingmember and the platform, and across the abutment member and theplatform, and adapted upon the cable shearing or coming adrift toseparate the abutment member and the locking memberV and to move the 2locking member to engage its abutments with the guideways whereby thesaid stop will, under the iniiuence of the weight of the platform causethe abutments on the locking member to bite against the guideways toarrest the platforms descent.

In order that the invention may be clearl understood and readily carriedinto effect, a sheet of drawings is appended hereto illustrating anembodiment thereof, and wherein,

Figure 1 is a front broken elevation view showing the platform adaptedto a hoist similar to that described in co-pending application No.18,276 of 1946 and with the platform supported by the cable under normalconditions. Y

Figure 2 shows the relative positions of the platform and elements ofthe safety device immediately the cable breaks or comes adrift.

Figure 3 shows the safety device operative.

Figure 4 is a side elevation view of Figure l, and

Figure 5 is a broken perspective rear view showing the relativedisposition of the parts immediately the cable breaks or comes adrift.

Referring to the drawings, the platform frame I has two angle bar rearuprights 2 and 3, diagonal struts 4 across the tops of the uprights andthe platform frame I, angle cross bars 5, 6 and 'I welded to theuprights, and rollers 8 tracking the front angle bar members 9 and I il,of the main column of the hoist along which the platform is raised andlowered by suitable winding mechanism receiving a cable II guided over apulley I2 and anchored at one end to the top of the column and at theother end to a winch drum in Well known manner the pulley I2 issupported within? the forked upper end of a rod I3 guided through o thetransverse stay bars 5 and 6 and secured at itsl lower end in a lug I4(see Figure 5) formed on a transverse bar I5, so that in effect thecableA I IA can be regarded as connected to the transversebar I5 fordrawing the platform up the column bars 9 and I0.

` Two vertical coiled tension springs I6 and I'Iv are anchored at theirlower ends to the platform I, e. g. to hooks I8 on the lower ends of theplat;

form uprights 2 and 3, the spring I'I being anchored to one end of thetransverse bar I5 to which the cable receiving pulley I2 is connected,and the other end of this transverse bar which normally abuts againstthe adjacent edge of a gripper bar I 9 and the other coiled tensionspring I6 being anchored by a U-shaped shackle or stirrup 20 to theadjacent end of the gripper bar,

the lower end of this latter coiled tension spring' I6 being anchored tothe Aplatform and receiving the same load as the other spring I1 due tothe tension of the cable I I by reason of the fact that the adjacent endof the transverse bar I5 abuts against the appropriate end of thegripper bar I9 as shown in Figure 1.

It will be appreciated that by reason of the rod I3 being guided throughthe two bars 5 and 6 the transverse bar I5 is always maintainedhorizontal, or normal to the main column, and consequently it willnormally abut flush against and maintain the Igripper bar I9 horizontalas shown in Figure 1, a stop lug or block 24 on the platform upright 2,limiting the Itension on the springs I6 and I'I, this lug-or block 24functioning as part of the means to bring the safety device intooperation as hereinafter described.

The gripper bar I9 is provided with two abutments 2l and 22 adapted toengage the said angle-section front bars 9 and I0 of the hoist columnwhen the cable breaks or comes adrift, and. the abutment 22 on thegripper bar I9 at theend adjacent the end of the transverse bar I5 towhich the coiled tension spring II is anghored is of wedge or Acube formwith one edge ngr-mally slightly spaced from the adjacent hoist framemember I0. The other abutmentf2I, i. e. the abutment on the end of thebar I9 to which tliekother coiled tension spring I6 is anchoredpreferablyV has a polygonal, e. g. hexagonal periphery, to engage thecolumn frame member 9-- and isnormally clear of the member 9 but isadapted to provide a fulcrum point about which the gripper bar I9 canswing through a small angle into acute angular relationship with thetransverse bar I5 ,when the safety device comes into operation as shownin Figures 2 and 3.

The median part of the gripper bar I9 is formed with a V-shaped notch23, or with a proud inverted V-shaped projection normally resting over afulcrum pin 24 xed to the centre of the cross bar 5 of the platformframe.

, Welded onto,or otherwise fixed to, the vertical frame member 2 of theplatform adjacent the end of the ,gripper bar `I 9 to which theappropriate coiled tension spring I6 is anchored is the aforesaid stoplug or block 24, and this is adapted, in the event of the cable breakingor coming adrift, to yultiniately abut against the upper edge of thelatter end of the gripper bar I9 as shown in Figure 3, the/arrangementlbeing such that immediately the cable II breaks, or comes adrift, thevgripper bar I9 is pulled about the fulcrum pin 24 by the spring I6 intoanl inclined or diagonal position relatively to the platform as shown inFigure 2 resulting in the edge of the abutment -2I on the [bar I9engaging the associated hoist column member 9 and the other abutment 22biting by a corner against the associated hoist columnmember I0.Immediately after the bar I9 has moved into this diagonal position thefulcrum pin 24' leaves the inverted v-shaped notch 23 of the bar I9 asshown in Figure 3, this being due to a slight displacement of theplatform relatively to the gripperv bar, the lug or block 24 beingcarried by the weight of the platform hard against the `appropriate endofthe gripper bar so that the gripper bar becomes wedged diagonallyacross the frame members 9 and IIJ of the hoist and thereby affords ahighly positive gripping means preventing further descent of theplatform, it being apparent that the heavier the lead on the platformthe greater the grip of the said abutments against lthe frame members.

.fI claim:

l. In combination a khoist column incorporating guides, a platform, acable from which the platform is suspended and by which it is pulled upand lowered down the guides, a locking bar carried by and displaceablerelative to the platform and spanning the said guides, relatively fixedabutments on said bar disposed adjacent to but normally not positivelyengaging the guides so that the locking bar is normally inoperative,means on the platform to actuate the locking bar to the operativeposition and normally subjected to the tension of the cable and therebymaintaining said locking bar in the said inoperative positionalrelationship with the platform and guides but adapted upon the cableshearing or coming adrift to cause a tilting of said locking bar tobring ksaid abutments hard against the guides and thereby to lock theplatform against further descent.

2. In a hoist in which a cable suspends a hoist platform and isconnected to winding means for dra-wingrthe platform, along guideways of.the hoist, safety-means to lock the platform against descent in theevent of the cable breaking o r coming adrift, said Vsafety meanscomprising a cable anchorage member carried by the platform and alocking bar spanning the said guideways, abutments on said bar adapted,when the cable breaks or cornes adrift, to bite against the saidguideways but normally held lclear of said guideways, a stop for thelocking bar on the platform, said anchorage member under the tension vofthe said cable being held against the locking bar to hold the lockingbar due to the tension of the cable `in the normal or inoperativeposition against said stop on the platform with the abutments on the barnotmbiting against the guideways, spring meansyieldingly opposing thetensipn of the cable being yprovided across the locking bar and theplatform, and across the anchorage member and the platform, and adaptedupon the cable shearingor coming adrift to separate the -anchoragemember and the locking bar yto movethe llocking bar` to engage itsabutments with the guideways whereby the said stop will, under theinfluence of the weight of the platform, cause thelocking bar to tilt tocause the abutments on the locking bar Vto biteagainst the guideways toarrest the platforms descent.

3. In combinationa hoist column with guideways, a Aplatform running -upand down the guideways, a cable by which the platform is connected tothe power driven means for raising and lowering the platform, a gripperbar loosely spanning vthe Vertical .guideways and formed with abutmentswhich .during the normal raising and lowering of -the'platform haveaslight clearance from the said guideways, spring means tending todisplace the saidl gripper bar from its aforesaid normal or inoperativeposition into an inclined position relatively to the platform so as toengage the abutments on the gripper bar with the, said guideways,`,whereby due to the said inclination of the gripper bar and the weightof the platform the gripper bar becomes wedged across the guides orappropriate frame members to arrest descent of the platform, and aconnection from the cable tothe said spring means which normallyovercomes the aforesaid tendency of the spring means to displace saidgripper bar into the .operative position.

4. A, safety device for use with up and down travelling `platforms ofhoists in which the hoist embodies vertical-frame elements forming acolumn and in which the platform is pulled up and lowered down parallelguideways of the column by a cable adapted to be driven from a powerunit, comprising a tiltable locking bar connected, but angularlydisplaceable relative, to the platform and common to and overlappingvertical frame elements of the column, relatively fixed abutments onsaid locking bar between which the latter frame elements are located,the abutments normally being disposed close to but clearing said latterframe elements, spring means tending to tilt said locking bar relativeto the platform so as to cause the said abutments to bite hard againstthe said latter frame elements and to seize the bar immovably acrosssuch frame elements to arrest descent of the platform, and` a connectionfrom the cable to said spring means which normally overcomes theaforesaid tendency of the spring means to displace the said locking barinto the operative position.

5. A safety device for hoist platforms in which a cable carried up thehoist from the platform is connected to the power operated means forraising the platform along parallel guides of the hoist, comprising asubstantially horizontal abutment bar carried by the platform anddisposed across one face of the parallel guides and to which the cableis connected to apply lift to the platform, spring means connectedacross one end of this abutment bar and the platform, a locking barfulcrumed between its ends to the platform frame, and located above andengaged by said abutment bar so that normally the abutment barlies flushagainst the parallel superposed locking bar, further spring means towhich the end of this locking bar remote from the spring loaded end ofthe abutment bar is connected to the platform, both of said spring meanscombining to yieldingly oppose the cables tension, the platform having arelatively fixed stop normally engagingthe upper edge of the locking barand between which and the abutment bar the spring loaded end of thelocking bar is located, two abutments on the locking bar disposed closeto but normally spaced beyond the e-dges of the said parallel guidesagainst which they are adapted to bite when the cable shears or comesadrift due to the weight of the platform being applied to the springloaded end of the locking bar by said stop, said fulcrum of the lockingbar affording a centre of leverage for such bar when the spring meansloading the locking bar is permitted to reassert itself but the lockingbar being freed from its fulcrum consequent upon the full weight of thearrested platform wedging the abutments on the locking bar against theguides.

6. A safety device to arrest descent of a hoist platform down guidewaysof the hoist consequent upon the shearing or coming adrift of a cable ofthe hoist by which the platform is connected to means for pulling it upand lowering it down the platform, comprising a locking bar with tworelatively fixed abutments and carried relatively tiltably by theplatform and spanning the guideways, spring means receiving the liftingtension of the cable and normally maintaining the locking bar in suchposition that its abutments are located close to but spaced from theguideways, and adapted consequent upon the tension of the cable beingreleased therefrom to assert itself to tilt the locking bar so as tobite its said abutments against the guideways and arrest-the descent ofthe platform.

RE GINALD FRANK WARRY.

REFERENCES CITED UNITED STATES PATENTS Name Date Hinkel Dec. 1'7, 1907Number

